1. Field of the Invention
The present invention relates to a magnetic resonance imaging apparatus provided with a phased array coil that includes a plurality of local coils arranged so that the sensitivity area of each local coil overlaps with that of at least one of the other local coils, and relates to a control method for controlling the apparatus.
2. Description of the Related Art
Magnetic resonance imaging (MRI) apparatuses of this type synthesize images based on the outputs of the local coils incorporated in a phased array coil (PAC), thereby reproducing a single image. Accordingly, even if some local coils are abnormal, an image can be reproduced based on the outputs of the other normal local coils.
However, since even the outputs of the abnormal local coils are also synthesized, the signal-to-ratio (SNR) is reduced, degrading the quality of the resultant image. It is difficult for users to determine whether degradation in image quality is caused by some abnormal local coils, with the result that the use of the abnormal local coils may well be continued.
Jpn. Pat. Appln. KOKAI Publication No. 2002-355233, for example, discloses a magnetic resonance imaging apparatus, in which pre-scanning is executed using all local coils to detect any local coil that has a sensitivity area falling outside an area preset for photography, and such a local coil is not used for actual image scanning. In this magnetic resonance imaging apparatus, an abnormal local coil may be considered to have a sensitivity area falling outside the preset area, and hence may not be used for actual image scanning. In this case, however, just because the abnormal local coil is not used, the existence of the abnormality itself is difficult for users to detect.